Capsules are a dosage form in whcih a useful agent is enclosed within a wall. Capsules are a popular method for administering a useful agent in both prescription practice and in over-the-counter practice, and they are widely used in hospitals, in homes, and in other environments. Capsules enjoy this popularity because they are tasteless, essentially innocuous, easily administered, and they are easily filled extemporaneously or in large numbers. Additionally, some users find it easier to swallow capsules than other dosage forms.
While these advantages and preferences have lead to the continuing acceptance of capsules, there are certain short comings associated with capsules. For example, capsules give up all their useful agent immediately to the environment of use, with the consequence that useful agent concentration is high initially followed by a low concentration, or by a total absence of useful agent between later administered capsules. For many useful agents this form of administration can have undesirable effects, especially if the useful agent has a low therapeutic index and is not suited to time-varying rates of administration. Another shortcoming associated with capsules is they are poorly suited for administering useful agents with short biological half-lives, and this results in exclusion of a large number of useful agents including mammalian biochemicals, natural hormones, humoral factors, and the like.
Yet another shortcoming associated with capsules is their instant delivery of a useful agent and its accompanying detrimental effects. Because of this, capsules require a high frequency of use, and this often leads to a failure of patient compliance for a prescribed dosage schedule. Such failures are reflected in a lack of therapeutic effectiveness and in possible toxic effects. The latter effects can occur when patients double or triple their dosage to compensate for their prior omissions. Faulty compliance accompanying the use of capsules is a common and largely ignored problem.
It will be appreciated by those versed in the art in the light of this presentation, that if an osmotic capsules can be provided that is free of the tribulations known to the prior art, such an osmotic capsule would have a positive, practical value and it would also represent an advancement in the delivery art. The present invention advances the state of the delivery art by providing a delivery system manufactured as an osmotic capsule for optimizing the beneficial effects of a useful agent. The osmotic capsule administers the useful agent at a programmed and controlled rate for a prescribed period of time. The osmotic capsule provides continuous control over the administration of the useful agent, and it maintains this control over an extended period of time.